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Diffstat (limited to 'docs/users_guide/using-concurrent.rst')
| -rw-r--r-- | docs/users_guide/using-concurrent.rst | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/docs/users_guide/using-concurrent.rst b/docs/users_guide/using-concurrent.rst index c00a294132..2621afce0f 100644 --- a/docs/users_guide/using-concurrent.rst +++ b/docs/users_guide/using-concurrent.rst @@ -107,11 +107,14 @@ RTS options for SMP parallelism There are two ways to run a program on multiple processors: call ``Control.Concurrent.setNumCapabilities`` from your program, or use the -RTS ``-N`` option. +RTS ``-N`` options. ``-N⟨x⟩`` +``-Nmax⟨x⟩`` + .. index:: single: -N⟨x⟩; RTS option + single: -Nmax(x); RTS option Use ⟨x⟩ simultaneous threads when running the program. @@ -133,6 +136,9 @@ RTS ``-N`` option. value of ⟨x⟩ itself based on how many processors are in your machine. + With Nmax⟨x⟩, i.e. ``+RTS -Nmax3 -RTS``, the runtime will choose at + most (x), also limited by the number of processors on the system. + Be careful when using all the processors in your machine: if some of your processors are in use by other programs, this can actually harm performance rather than improve it. |